I rewired the 700r4 by deleating the temp.sw.,grounding the t.c.c. solenoid & ran the pos. wire of solenoid to term. A. Then 4th pressure sw. with 1 connection,ran that wire to term. B.Now I'm going to use a vac.sw. I got off a 83 p/u,it breaks at 7.5in vac. its normally closed like the pressure sw. is.Tested vac.sw. with light bulb gave it voltage light came on,applied vac. light went off at 7.5 vac. Same with pres. sw. gave it voltage light came on, applied air light went off.So my question is when at high vac. their is voltage going to pres. sw. & t.c.c. solenoid & locked up,low vac. no voltage & it's not locked up. That's how it works, right? Next question is what is the the correct connection for the vac. sw. Should I use the port where I had the TH350 vac.mod. connected to (manifold vac.) or to the carb. ported or unported? I found these vac.sw. on 83-85 Chevy p/u, by the brake booster mounted on the firewall.Theirs 2 different kinds,one with a square metal plate,these brake at 5in. vac., the other has a round metal plate, breaks at 7.5in. vac. F.Y.I. One more thing G.M. doesn't make them anymore, & most autoparts stores don't know what they are. Couldn't find a new one. I know TCI & PATC has them but I'm a cheap basturd.